Internal combustion engines operate by the combustion of fuel in one or more combustion chambers. In fuel-injected engines, one or more fuel injectors are mounted to the engine to supply the fuel to each combustion chamber. The fuel is stored in a fuel tank, and is typically supplied to the fuel injectors from the fuel tank via a vapor separator, a fuel pump and a fuel rail. A pump draws fuel from the fuel tank and supplies it to the vapor separator. The vapor separator removes vapor from the fuel. The fuel pump draws liquid fuel from the vapor separator and pumps the liquid fuel through a high-pressure fuel line to a fuel rail. The injectors draw fuel from the fuel rail and deliver the fuel to the combustion chambers. The quantity of fuel supplied to the combustion chambers is regulated by the injectors. The fuel pump generally supplies more fuel than is needed by the injectors, to ensure an uninterrupted fuel supply. A fuel return path is provided from the fuel rail to either the fuel pump, the vapor separator or the fuel tank, for returning excess fuel that is supplied to the fuel rail and not used by the injectors.
While this system is adequate for supplying fuel to an engine, it has a number of drawbacks. Assembly of the fuel supply system described above requires many components to be interconnected. Some of the components can be difficult to align during assembly, and many individual connections must be made between components, resulting in increased manufacturing cost. In particular, the high-pressure fuel line is relatively expensive as it must be manufactured to withstand the high pressure of the fuel exiting the fuel pump. In addition, the multiplicity of components increases the chance of failure of any one component, such as a leak in the high-pressure fuel line, which may interrupt the adequate supply of fuel to the engine. In addition, the multiplicity of components makes it more difficult to obtain a compact arrangement, which is desired in some applications such as in marine outboard engines.
Therefore, there is a need for a fuel injection system of an engine having a reduced number of parts.
There is also a need for a fuel injection system having a compact arrangement.
There is also a need for a fuel injection system having increased ease of assembly.